Ultrastructural characterization of genome of epizootic hemorrhagic disease virus.

Purified epizootic hemorrhagic disease (EHD) virus preparations were treated with urea and sodium perchlorate. The viral ribonucleic acid (RNA) released when spread on protein monolayers according to the Kleinschmidt technique was examined by rotary shadow-casting electron microscopy. The viral RNA released by urea treatment had filaments which frequently formed three to five loop-shaped figures of varied length. In 80% of the virus particles the lengths of the viral RNA released were 2.5 to 4.5 mum. The sodium perchlorate-released viral nucleic acid also appeared linear, and about 70% had lengths of 0.1 to 2.0 mum, the longest filament measuring 5.8 mum. Evidence was obtained that EHD virus contains double-stranded RNA as its genetic material and the molecular weight of the EHD viral RNA was calculated to be 12.2 x to 10(6) to 15.1 x 10(6) daltons.